Automotive and truck tires may be recycled and processed into “crumb” rubber or rubber chips. During the recycling process, the steel belts and tire cord, sometimes known as “fluff”, is removed leaving particles of rubber with a granular consistency. The steel and fiber removed during the process may also be recycled. The granular particles of crumb rubber have been used in asphalt base, artificial turf base, athletic field cover, beneath playground equipment and in other products as a cushioning material.
Crumb rubber may be provided by recycling operations in various sizes. The crumb rubber granulate is passed through a screen with a known number of holes per inch. For example, size 10 crumb rubber has been passed through a screen with 10 holes per inch such that, depending upon the gauge of wire used in the screen, the size of the rubber granulate passing through the screen is slightly less than one-tenth of an inch. Similarly, size 20 crumb rubber passes through a screen with 20 holes per inch and has a size slightly less than one-twentieth of an inch. Size 2 crumb rubber would be slightly smaller than one-half inch having been passed through a screen with 2 holes per inch.
Crumb rubber may generally be graded or classified on a scale of 1 through 5 according to standard industry practice. No. 1 crumb rubber is granulated tire crumb which is black only (white portions/sidewalls are not included), metal free (but not magnetically separated) and with the “fluff” from tire cord removed. No. 2 crumb rubber may include white sidewalls portions. No. 3 crumb rubber may include black crumb only but may be magnetically separated from metal particles. No. 4 may be black and white crumb which has been magnetically separated and No. 5 may be unseparated and include fluff. Thus No. 1 crumb is preferred for some applications while No. 5 crumb may be used for applications not requiring a clean material
In many construction sites, government environmental regulations require some form of temporary erosion control to prevent or mitigate soil, rock or other debris which has been displaced by construction activities from being carried by water or other liquids into storm water drains or other water drainage areas such as lakes and streams. Such sediment control program may sometimes be referred to as a “BMP” or Best Management Practice. In many situations, fiber rolls or straw “wattle” have been used as a BMP. In a fiber roll, straw, coconut fiber or similar material is bound between plastic mesh and made into sheets or tubular rolls of material. The fiber rolls trap sediment and may be used in place of straw bales or sand bags, which have also been sometimes used. Another commonly used tool is the “rock sock” which is a water permeable cloth enclosure containing rock or gravel.
Straw wattle suffers from being non-reusable and may fall apart or decompose, especially when wet. While lightweight when dry, it becomes much heavier when liquids such as water are absorbed by the straw which also makes the straw wattle prone to break apart and complicate its relocation or reuse. In situations where straw wattle is used on roadways, vehicle traffic may contribute to breaking apart of the relatively fragile straw wattle. Because straw wattle is relatively lightweight when dry, it may be carried away by wind, foot or vehicle traffic, or an initial high liquid flow unless properly secured or staked into the ground. In situations where used on hard surfaces, such as paved streets, straw wattle must be anchored by other means, such as sand bags or concrete blocks, to avoid being carried off by liquid flow, wind, or pedestrian or vehicle traffic.
Straw wattle, rock socks and sandbags are also limited because they may be difficult, or impossible, to clean once they have been infused with sediment or other debris from water runoff. They are thus generally limited to one-time use which can make their use more expensive. They also present a disposal problem in that they must be properly disposed of once they have served their purpose of capturing sediment or other debris. In the case of rock socks, the rock must be removed and the material enclosure must be replaced once it is worn or cannot be cleaned. The rock must then be placed into a new or cleaned synthetic or cloth “sock” which may be time consuming and impractical.